This application relates to bulldozers or earth-working machines having ground-engaging, material-moving blades and more particularly to an improved and simplified mechanism for angling, tilting, and pitching the material-moving blade.
It is known to provide bulldozers or earth-working machines with a pusher frame of C-shaped configuration that fits between track frames and the front end of a tractor for driving the blade. The rear ends of two arms of the C-shaped frame are pivotally connected to sides of the tractor frame and permit vertical raising and lowering of the C-shaped frame about a transverse axis. This permits the blade to be moved from a ground-working position to a transport position.
A known prior art device disclosed in U.S. Pat. No. 4,201,268 was invented by the inventor of the present application. In this device a frame extends along, and defines, a longitudinal axis. The blade is driven to pitch by rotating about an axis transverse to this longitudinal axis, angle about an axis extending vertically from the longitudinal axis, and tilt about the longitudinal axis. In this prior art device, the pitching and angling are provided by a pair of hydraulic cylinders while the tilting is provided by a single hydraulic cylinder. The cylinders are all pinned to the frame. While this type of prior art device has proved quite beneficial, it is now desired to further improve this mounting arrangement.
In the prior art some difficulty was encountered in connecting the necessary hydraulic cylinders to the blade and frame. Since the blade moves about three axes relative to the frame, the connections were complicated.
Also, a blade is usually driven to pitch or tilt through only a small angular extent while normally driven to angle through a greater angular extent. For this reason, it may be beneficial to provide both the tilting and the pitching with a pair of hydraulic cylinders and the angling with a single cylinder. The prior art cyliner construction and circuitry had to provide for both accurate small movements for pitching and relatively greater movement for angling. It can be difficult to achieve both goals. In addition, the prior art may not always have adequately guided the blade as it angled relative to the frame.
It is therefore an object of the present invention to provide an improved tilt-pitch-angle mechanism for attaching a dozer blade to a frame in which the movement of the blade about the three axes relative to the frame is achieved in a simplified manner while ensuring that the blade is accurately guided about the axes.